My father was preparing for his speech __ my mother was doing some washing last night.
A.if B.while C.unless D.until
Our world will get better and better each of us lives a greener life.
A.before B.if C.though D.until
Eric arrived on time, _______ it was the rush hour.
A. though B. because C. while D. unless
(2017河北34题)Mom won't let Dick go out ________ he promises to be back by 10：00 tonight.
A.if B.when C.since D.unless
Bob, dinner is ready. Please wash your hands ________ you eat.
A.until B.after C.while D.before
Be more careful and more patient, ________ you will make fewer mistakes in the following experiments.
